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    <title>Document</title>
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<body>
    <ul>
        <li>这是1个</li>
        <li>这是2个</li>
        <li>这是3个</li>
        <li>这是4个</li>
        <li>这是5个</li>
    </ul>
    <script>
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        for(var i = 0 ; i < lis.length ; i++){
            //获取每一个li
            // console.log(lis[i]);
            lis[i].onclick = function(){//调用者是谁?
                console.log(this);
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